check process isc-dhcp-server with pidfile /var/run/dhcpd.pid
  start program = "/bin/systemctl start isc-dhcp-server.service"
  stop  program = "/bin/systemctl stop isc-dhcp-server.service"
  if failed host 127.0.0.1 port 67 type udp then alert
  if 5 restarts within 5 cycles then timeout
